Dr. Ahmad Redaa
2025-08-26
Layers of the Earth
- Crust: Composition, continental vs. oceanic
- Mantle: Structure, composition, convection
currents
- Core: Inner and outer core, composition,
geodynamo
The Earth’s interior, Source: Philpotts and Ague (2022)
The layers of the tectonic Earth, (Source: Philpotts and Ague (2022))
Generalized cross section illustrating magma generation associated with various plate tectonic settings. Source: Winter, J. (2014)
Decompression melting
Pressure decrease lowers the melting point of mantle rocks.
Tectonic settings: mid-ocean ridges, mantle plumes →
basaltic magma
Flux melting (addition of water)
Water released from a subducting slab lowers the mantle solidus.
Tectonic settings: subduction zones → andesitic
magma
Heating of crust
Basaltic magma underplates the continental crust and transfers
heat.
Tectonic settings: continental crust → granitic
magma
Partial melting
Melting begins at mineral grain junctions; most magmas are mixtures of
melt and crystals.
Result: porphyritic textures common in igneous rocks
The convergent plate boundary (Source: Jain, S. (2014))
The Ocean–Ocean convergence (Source: Jain, S. (2014))
The Ocean–Continent collision (Source: Jain, S. (2014))
The Divergent Plate Boundary (Source: Jain, S. (2014))
The East Africa Rift Valley and the Red Sea rift (Source: Jain, S. (2014))
Schematic model for oceanic volcanism. Source: Winter, J. (2014)